白沙蒿种子萌发特性的研究 I. 粘液瘦果的结构和功能

白沙蒿(Artemisia sphaerocephala Krasch.)是中国西北部沙漠的流动及固定沙丘上广泛分布的优势种灌木。瘦果小而轻,借助显微镜和扫描电镜对瘦果的形态结构进行了观察,其种子的种皮与果皮愈合,果皮外层为很厚的粘液层,其粘液层在遇湿后迅速吸水膨胀,其重量增至原来的589倍。在自然生境中,粘液物质将沙粒粘附于瘦果的周围,使瘦果的重量发生变化。瘦果能长时间在水上漂浮,粘液物质有助于种子的萌发和苗的发育。白沙蒿产生三种不同颜色的瘦果,其种子具有不同的萌发速率但最终达到相同的萌发率。研究表明瘦果的粘液物质对白沙蒿种子的传播与萌发具有重要的生态意义。     

白沙蒿种子萌发特性的研究 II. 环境因素的影响

白沙蒿(Artemisia sphaerocephala Kraseh．)是中国西北部沙漠的流动及固定沙丘上广泛分布的优势种灌木。白沙蒿种子为需光种子,种子在光下萌发而在黑暗中受到抑制。种子萌发的适宜温度为25℃,在10℃和30℃萌发速率和萌发率都很低,萌发在5℃受到抑制。种子在沙中被埋越深,其萌发速率和萌发率就越低。在沙平面下2cm或更深层沙土下出苗率为零。但是,当将种子上层沙土移走,只保留0.5cm沙土覆盖种子,这些种子的萌发率达到原先就位于沙土下0.5cm的种子的萌发率,但是后者的萌发速率较高。土壤水分含量越高,从1.7％到14.7％,其萌发就越快。土壤水分含量从19.4％起,种子的萌发受到了延迟,苗的发育受到了抑制.     

西鄂尔多斯珍稀濒危植物长叶红砂种子萌发特征

珍稀濒危灌木长叶红砂是我国西北干旱地区荒漠植被中的古老残遗物种,对维持荒漠植被稳定具有重要作用.本文研究了长叶红砂种子特性,及其在不同光照、温度、土壤水分和沙埋等环境因子中的萌发策略.结果表明:长叶红砂种子具有高活力、高萌发率、耐贮存的特点,在光照和黑暗条件下均能很好地萌发.种子萌发的适宜温度为恒温20 ℃～25 ℃或变温15 ℃/25 ℃,萌发率高达93%.土壤含水量为2%时,种子开始萌发;土壤含水量为12%时,其萌发率最高,达89%.长叶红砂种子适宜的沙埋深度为1 cm,＞5 cm沙埋不出苗.沙埋深度对出苗率和幼苗生长高度的影响显著,而对幼苗质量的影响不显著.水分条件和沙埋深度是制约长叶红砂种子萌发和出苗的主要因素,而种子的高萌发率增加了幼苗生存的风险,不利于其应对荒漠极端环境变化.这种特性是长叶红砂濒危的重要原因之一.     

黑沙蒿资源的综合开发利用研究

对黑沙蒿的生物学特性、化学成分及开发应用进行了综合研究。结果表明：黑沙蒿是理想的抗旱、防沙和固沙植物;合有丰富的营养物质,可作为畜牧业的重要饲料;有较高的药用价值和工业利用前景,对该植物资源的开发利用提供了科学依据。     

Effects of burial in sand and water supply regime on seedling emergence of six species

BACKGROUND AND AIMS: Air seeding has long been regarded as a quick and successful measure for vegetation rehabilitation in China. However, seedling emergence of often-used species including Agriophyllum squarrosum, Artemisia sphaerocephala, Artemisia ordosica, Hedysarum fruticosum, Caragana korshinskii and Medicago sativa is low. Experiments were conducted under controlled conditions to study the effects of sowing depth and water supply on seedling emergence, in order to understand the requirements for increasing seedling emergence. METHODS: Seeds were exposed to different environments of burial and water supply regimes in PVC pots (7 cm in diameter and 11 cm in height) under the same light intensity and alternating temperature regimes in a growth chamber. KEY RESULTS: Seedlings of three species (Agriophyllum squarrosum, Artemisia sphaerocephala, Artemisia ordosica) with relatively light seeds emerged well at a 0.5 cm sowing depth under a 7.5 and 10 mm water supply regime. However, few seedlings of these species emerged when the sowing depth was over 1 cm or when water supply was 5 mm. Seedlings of Caragana korshinskii, Hedysarum fruticosum and Medicago sativa emerged from sowing depths of 0.5-4 cm, 0.5-3 cm, and 0.5-4 cm, respectively, under both 7.5 and 10 mm water supply regimes. Under a 5 mm water supply regime, seedlings of these species also emerged at over 1 cm sowing depth. Seeds of all six species sown on the surface of sand did not germinate, and seedlings did not emerge when they were sown at depths greater than 6 cm. CONCLUSIONS: Based on these experiments, a 0.5 cm sowing depth resulted in the highest seedling emergence and it is concluded that this is the optimal sowing depth for seedling emergence of all six species.     

沙蒿与油蒿灌丛的防风阻沙作用

沙蒿与油蒿广泛分布于我国沙漠地区,是沙地植被的重要建群种和优势种。在腾格里沙漠南缘半流动沙地,实测了两种典型固沙植物沙蒿与油蒿的防风阻沙作用,从灌丛空间构型对比分析了其防风阻沙机制。结果表明,沙蒿与油蒿灌丛均具有明显的降低风速作用,但油蒿灌丛较沙蒿灌丛具有更显著的防风作用,而且对灌丛后不同位置、近地面不同高度层风速的降低程度明显不同。在灌丛后6倍株高范围内,沙蒿灌丛对50cm高度风速降低程度显著大于20cm,而油蒿灌丛对近地面20cm高度层风速降低程度显著大于50cm。在相同风速下,油蒿灌丛后20cm高度平均风速是沙蒿灌丛的1/2,而50cm高度平均风速与沙蒿灌丛相近。同时,沙蒿灌丛阻沙作用弱,而油蒿灌丛具有明显的阻沙作用,单株积沙体积达到45.2±16.1dm3,积沙重量达到72.1±25.7kg,油蒿灌丛积沙量大小与灌丛结构间存在显著的正相关。研究表明,紧密型结构的油蒿灌丛是较松散型结构沙蒿灌丛更为理想的防风固沙植物,其灌丛分枝数多、分枝角度小、生物量大且多分布在近地面层是具有显著防风阻沙作用的根本原因,该结论可为干旱区防风固沙植被建设物种选择提供依据。     

荒漠植物种子逆境萌发研究进展

对水分、温度、光照、沙埋深度、盐分胁迫及以上几种综合因素在逆境条件下对荒漠植物种子萌发的影响进行了综述。降雨次数、雨量大小、分布及土壤湿度是决定荒漠植物种子萌发的重要生态因子;温度是影响荒漠植物种子萌发的关键生态因子之一,变温有利于荒漠植物种子萌发;光照并非大多数荒漠植物种子萌发的必要条件,少部分荒漠植物种子萌发需要光照,有些要在黑暗中萌发,有些则对光照无特殊要求,光照对有些荒漠植物种子萌发有一定的抑制;不同沙埋深度具有不同的土壤湿度,土壤温度和光照等条件,综合调控荒漠植物种子的萌发;盐分胁迫抑制种子的萌发。荒漠植物种子的萌发在以上几种因素的共同协调作用下表现出一定的适应性。随着研究的不断深入和生态环境建设的需求,需要加强荒漠植物生理生态研究的深度和研究的系统性。     

毛乌素沙地3种优势植物对模拟降水量变化的水分平衡研究(英文)

未来全球变化 ,尤其降水变化的进一步加剧 ,将对毛乌素沙地陆地生态系统分布格局和生产力带来巨大影响。为了预测未来变化 ,提出合理的对应策略 ,实验选择毛乌素沙地 3种优势灌木、半灌木为研究对象 ,人工控制 4种降水量水平来探讨水分平衡对全球降水量变化的响应。结果表明 ,沙地蓄水量和不同沙层深度含水量季节变化明显受到不同施水量和 3种植物种类的影响。 3种植物沙地蓄水量和不同深度沙层含水量随着施水量的增加逐渐增大 ,并且不同施水量和植物沙地含水量随深度增加逐渐增大。在同一施水量处理下的蓄水量和同一深度含水量均大体为杨柴 (HedysarummongolicumTurcz.) >沙柳 (SalixpsammophilaC .WangetCh .Y .Yang) >油蒿 (Artemisiaordosi caKrasch .) ;3种植物的蒸发量和蒸腾量季节变化明显受到施水量的影响。随着施水量的增加 ,即 15 7 5、315 0、472 5和 6 30 0mm ,蒸发总量依次为 12 3.6 6、2 5 8.6 8、376 .30、45 8.5 7mm ;蒸腾总量 ,油蒿分别为 5 0 .80、6 8.93、10 8.39、16 3.36mm ;沙柳分别为 47.37、6 8.17、93.6 5、135 .97mm ;杨柴分别为 46 .73、6 7.37,86 .0 7、10 9.6 4mm。蒸发量显著大于蒸腾量     

Study on the Water Balance in Three Dominant Plants with Simulated Precipitation Change in Maowusu Sandland

The distribution pattern and productivity of Maowusu sandland terrestrial ecosystem are greatly affected with the future severe global change, especially global precipitation change. Considering the predicative global precipitation change and the appropriate relevant strategy for the sustainable development of the China dry territory, the authors have investigated the response of water balance to global precipitation change by creating an artificial control of four levels of water supply treating 3 dominant plants in Mauwusu sandland. The results showed that the seasonal changes of water storage and moisture of different sandland layer depths were affected by different water supply treatments and different plants. The water storage of the three plant growing sandlands and the moisture of different sandland layer depths increased as water supply was increased. The moisture of different water supply treatments and plants increased with the increase of sandland layer depth. The water storage and moisture of the same layer depth of Hedysarum mongolicum Turcz. growing sandland were larger than that of Salix psammophila C. Wang et Ch. Y. Yang growing sandland, which were in turn higher than that of Artemisia ordosica Krasch. growing sandland in the same water supply treatment. Water supply significantly affected the seasonal changes of evaporation and transpiration of the three plant growing sandlands. With the increased levels of water supply, viz. 157.5 mm, 315.0 mm, 472.5 mm and 630.0 mm, the total evaporation was 123.66 mm, 258.68 mm, 376.30 mm, 458.57 mm, respectively, and the total transpiration of A. ordosica was 50.80 mm, 68.93 mm, 108.39 mm, 163.36 mm, respectively, and that of S. psammophila , 47.37 mm, 68.17 mm, 93.65 mm, 135.97 mm, respectively, and that of H. mongolicum 46.73 mm, 67.37 mm, 86.07 mm, 109.64 mm, respectively. Evaporation was significantly higher than transpiration in the experiment.     

不同风沙条件对几种植物生态生理特征的影响

 在野外风洞条件下,就不同风况的风沙胁迫对几种固沙植物生态生理特征的影响进行了实验研究。实验采用了沙坡头地区的野外植物和盆栽植物。在不同风速(5.9 m·s-1, 7.9 m·s-1, 9.9 m·s-1,14 m·s-1, 10 m·s-1,15 m·s-1, 20 m·s-1)和吹袭时间间隔(2 d, 4 d, 9 d)下测定了植物3个生理生态参数的变化。实验结果表明：1）净风和风沙流胁迫均可使植物的净光合速率（Pn）降低,蒸腾速率（E）升高,从而导致水分利用效率（WUE）下降。净风和风沙流对植物生理生态特征的影响显著不同。同样为14 m·s-1的风速时,风沙流使植物的Pn降低40.7%,而净风使其降低了35.88%。2）吹袭的时间间隔越短,植物的净光合速率降幅越大;风沙流比净风的影响更大。在2 d, 4 d, 9 d为间隔的风沙流吹袭下,油蒿（Artemisia ordosica）的Pn分别下降了20.13%、 11.76%、 7.72%。风沙胁迫强度越大,物质积累越少,植物的高生长越慢。3）由于风沙流降低了水分利用率,从而增加了对植物的干燥作用。从总体来看,沙生植物对风沙流胁迫有一定的适应响应,实验所用灌木较草本植物有更强的抗风性。     

Strong light inhibits germination of Artemisia sphaerocephala and A. ordosica at low temperature and its relevance to revegetation in sandy lands of Inner Mongolia, China

Artemisia sphaerocephala and A. ordosica are two dominant shrub species in Mu Us sandy land (Inner Mongolia, China) and are widely used for vegetation restoration. However, there are two different conclusions about the effect of light on their germination: light promotes germination versus light inhibits germination. The aim of this study was to evaluate these two conclusions and relate the results to instances of failure of these two species to germinate well when air-dispersed in revegetation projects. The effects of fluctuating temperature, light/dark, source (population), position on mother plant, storage condition, and storage time were tested on germination of achenes of these two species. At low temperature, final percent germination (FPG) of achenes in dark and nearly dark conditions was significantly higher than those in light. At 10:20°C, achenes of both A. sphaerocephala and A. ordosica had higher FPG in dark than in light regardless of source, position on mother plants or storage condition. At suboptimum (5:15°C) and supraoptimal (25:35°C) temperatures, germination of A. sphaerocephala and A. ordosica achenes was inhibited in both light and darkness. It was concluded that light inhibits germination of A. sphaerocephala and A. ordosica achenes at low (10:20°C) temperature but not at high (15:25°C) temperature. Since the temperature in Mu Us sandy land is around 10:20°C in early June, when air sowing is done, achenes should germinate best when they are covered by a thin layer of sand.     

毛乌素沙地4种沙生植物种子萌发及出苗对沙埋及单次供水的响应

飞播固沙作为一项快速而有效的现代化治沙措施,已成为毛乌素沙地植被恢复与重建的重要手段。但此项技术仍存在一些问题,如飞播后成苗率较低等。以毛乌素沙地优势植物柠条（Caragana korshinskii）、羊柴（Hedysarum laeve）、油蒿（Artemisia ordosica）与籽蒿（Artemisia sphaerocephala）为研究对象,人工控制7个沙埋深度和9个水分梯度,研究4种植物种子萌发和幼苗出土对沙埋和单次供水的响应,阐明多大的单次降雨才能保证种子萌发与幼苗出土及出土幼苗的维持时间。结果表明,对于柠条和羊柴质量相对较大的种子而言．种子主要在供水量10．20mm,埋藏深度为0．5．2cm的条件下出苗,但在埋藏深度为5cm时这两个物种仍有少量种子能够出苗;而对于油蒿和籽蒿质量相对较小的种子而言,种子主要在供水量10．20mm,埋藏深度为0．5cm时出苗,当埋藏深度为1．5cm和2cm时不能顺利出苗。沙埋深度0．5cm条件下,4个物种具有最高的出苗率和出苗速率。在试验期内（30d）,柠条、羊柴和油蒿出土幼苗分别在单次供水量为5、7．5mm和7．5mm时全部死亡,在单次供水量高于15mm时4个种的出土幼苗死亡率大多低于50％,且随供水量的增加出土幼苗死亡率降低。结合毛乌素沙地降雨特点与本次实验结果,0．5cm的沙埋及7．5mm以上的单次降雨是上述4种植物自然条件下出苗较好的重要条件。     

沙坡头地区人工固沙植物水分利用及其生态位适宜度过程数值模拟分析

本文以干旱区植物为研究对象,探讨了自然降水资源的时空分布规律以及降水与固沙植物耗水之间的制约关系。通过扩展经典生态位理论的内涵,用数学抽象的方法定义植物水分生态位适宜度为其水分最适生态位点与现实生态位的贴近度,建立相应的数学模型,对固沙植物生态位适宜度进行了定量分析,并建立了生态位适宜度过程模拟方法。依据实验结果进行了有关计算与数值模拟,所做模拟结果与实际观测结果相吻合。结果表明,柠条与油嵩混播为实验条件下的最佳种植方式,密度为5000株／hm^2时其水分生态位适宜度最高,林木覆盖率也最大。文中进一步讨论了有限降水限制和沙地土壤水分亏缺胁迫下油篙和柠条对水分的竞争行为,混播下的生态位适宜度变化及稳定共存格局形成的机理。该结果为干旱区人工林的营建提供了定量依据。     

实验室条件下两种生物土壤结皮对荒漠植物种子萌发的影响

生物土壤结皮广泛分布在干旱、半干旱区,深刻影响着土壤表层特性,进而对植物种子散布、萌发和定居产生极大的影响。到目前为止,生物土壤结皮与植物关系的研究很少见到,并且这些有限的研究所得出的结论存在着争议。研究了不同年龄的两种生物土壤结皮（苔藓结皮和藻类结皮）对油蒿（Artemisia ordosica）和雾冰藜（Bassia dasyphylla）种子萌发的影响,同时也研究了这两种结皮在失去活性前后对油蒿、雾冰藜和小画眉草（Eragrostis poaeoides）种子萌发的影响。苔藓和藻类结皮的出现对油蒿和雾冰藜种子的萌发均有显著的促进作用,而结皮年龄对植物种子的萌发没有显著的差异。对于不同的植物种,结皮类型和活性对种子的萌发具有不同的作用。雾冰藜在两种结皮上的萌发有显著的差异而油蒿和小画眉草在两种结皮上的萌发没有显著差异。活藻类显著地增加了三种植物的种子萌发,活苔藓仅增加了油蒿和雾冰藜种子萌发量而对小画眉草种子的萌发没有作用,研究表明,生物土壤结皮对一些植物种子萌发具有明显的促进作用。     

油蒿(Artemisia ordosica)的化感作用研究

通过对鄂尔多斯高原毛乌素沙地油蒿（Ａｒｔｅｍｉｓｉａ ｏｒｄｏｓｉｃａ）化感作用研究,发现油蒿茎叶的水浸提液对几种受体植物种子的萌发率,幼苗长和根长生长均有不同程度的抑制作用,随水浸提液浓度的增加抑制作用逐步增加;用油蒿茎叶水浸提液进行盆栽试验,受体植物的出苗率,苗高,根长和干物重也受到抑制,苗的形态也与对照有较明显的差异;     

毛乌素沙地半固定沙丘油蒿种群对土壤湿度空间异质性的响应

将统计学和地统计学方法相结合,探讨了毛乌素沙地半固定沙丘土壤湿度空间异质性与油蒿种群空间异质性之间的关系. 结果表明,在块尺度（80 m×80 m）上,油蒿密度和生物量的空间异质性受制于土壤湿度的空间异质性,尤其油蒿生物量的空间异质性与土壤湿度的空间异质性呈显著正相关关系.表明在半固定沙丘阶段,土壤湿度的空间异质性决定油蒿种群的空间异质性. 由于沙丘地形对降水量的再分配在土壤湿度分布中的作用,土壤湿度和油蒿种群空间异质性相互作用的结果为地形的缀块性→土壤湿度分布的缀块性→油蒿种群分布的缀块性→油蒿生物量和密度的缀块性.     

干旱半干旱地区人工固沙灌木林生态系统演变特征

应用实验生态学方法分析了沙坡头地区栽植于1956、1964、1981、1987年的无灌溉人工植被固沙群落浅层土壤分形特征、植被盖度、物种特征、生物量、土壤水分、土壤微生物,以及群落土壤物理和土壤养分特征,并与流动沙丘进行比较。结果表明,在干旱半干旱的草原化荒漠地区,首先利用半隐蔽式草方格沙障对流动沙丘进行固定,然后栽植灌木柠条、花棒等和半灌木油蒿,经过40多年的稳定演变,该区域逐渐形成由矮灌木与草本植物覆盖,以及隐花植物与微生物土壤结皮复合的固定沙丘景观。在人工植被固沙防护体系稳定演变过程中,浅表层土壤的细粒化和养分富集化特征,微生物土壤结皮与亚表层土壤厚度,以及浅表层土壤体积含水率均随固沙年限的延长趋于显著增加。而土壤微生物数量、植被盖度、植物种数等生物群落学属性在固沙年限达40a左右时,已趋于最大,尔后呈缓慢下降趋势。随着固沙年限的增加,灌木树种不断衰退减少,当固沙年限逾17a之后,群落生物量增至峰值后略有下降。土壤分形维数与土壤粘粒含量呈显著正相关关系,流动沙丘被人工植被固定年代越久远,浅表层(0~3cm)土壤粘粒含量(4.50%)越高,其分形维数越大(D=2.4083),表明人工植被固沙防护体系浅表层土壤结构变得越紧实,流动沙丘(D=2.0484)在人工植被的固定作用下,发生逆转的趋势越显著,沙丘日趋固定。     

Dispersion,germination and growth of seedlings ofSagittaria lancifolia L.

Sagittaria lancifolia L. a perennial helophyte growing in shallow waters has asexual reproduction by rhizomes and sexual reproduction by achenes. We studied the morphological characteristics of achenes related to its dispersion, some factors affecting its germination and the development stages and growth of seedlings. This species produces many achenes, and disperses through epizoochory and hydrochory. Achenes germinate on light only. 100% germination was obtained at 25°C. Under conditions of inundation the germination period decreases, and the percentage of germination in creases when compared to achenes with or without imbibition. Achenes in anaerobic conditions have reduced germination. The growth of seedlings ofS. lancifolia was affected by the temperature: each organ of the seedlings grows differently in dependence upon this factor. For example, roots grow faster during the early stages of the seedlings.     

毛乌素沙地沙丘土壤含水量特点——兼论老固定沙地上油蒿衰退原因

土壤表面干沙层在冬春少雨季节较厚,流动沙地的又明显地大于固和地的。流动沙地地表干沙层以下的土壤含水量一般在于同深化度固定沙地的,特别是在报系密集分布的土层。科季或早春土壤含水量比较低,雨季的明显较高,雨季结束后,土层中的水分在重力的作用下会向深层运动,导致根系层土壤含水量下降。在植物生长季,缺少降雨时,因少地的土土壤水量会因植物的蒸腾消耗而变得很低（１％～２％）,而流动沙地的不受或受此影响很小。地     

Seed germination and seedling emergence of three annuals growing on desert sand dunes in China

BACKGROUND AND AIMS: Information on the initial growth characteristics of annuals found in Chinese deserts is very limited. The aim of this study was to investigate seed germination and interactive effects of irrigation and seed burial depth in sand on seedling emergence and seedling survival in three annuals (Agriophyllum squarrosum, Bassia dasyphylla and Aristida adscensionis) commonly growing on sand dunes in these regions. METHODS: Effects of temperature, light and polyethylene glycol-6000 on seed germination were examined by irrigating seeds sown on filter paper in Petri dishes. Seedling emergence was examined for seeds sown on the surface of, or at different depths (5, 10, 20, 30, 40 and 50 mm) in, sand-filled pots, which were irrigated under different regimes. For seeds buried at a depth of 50 mm, seed viability was examined after irrigation of the pots. KEY RESULTS: Seeds of three species germinated at most temperatures recorded between spring and autumn in their native habitats. No seed dormancy was found in any species. For all three species, seedling emergence was most favoured when seeds were buried at a depth of 10 mm. When seeds sown on the sand surface were irrigated, seed germination was considerably suppressed due to water deficiency, but many seeds remained viable. For A. squarrosum and B. dasyphylla, many seeds that were deeply buried and irrigated remained ungerminated but viable, while for A. adscensionis deeply buried seeds germinated, but the seedlings did not emerge due to unfavourable seedling growth in deep sand. CONCLUSIONS: Precipitation is the most crucial factor in determining the seasonal emergence of seedlings of the three tested species in the field. The vertical distribution of seeds in sand determines the proportion of seeds that germinate after precipitation and acts to maintain seed banks over multiple years.